Because of an editing error, Jack Thompson was misidentified in an article about helicopters in Metro Sunday. He is president of the Mid-Atlantic Helicopter Association. (Published 9/1/87)

The already busy skies over Washington are becoming crowded with helicopters, reflecting the speed and ease of helicopter travel for government, military and private use at a time when local highways and runways are clogged with traffic.

Last month, 3,670 helicopters used the airspace controlled by the National tower, the area within a seven-mile radius of the airport. That is a 22 percent increase over the same month a year earlier. Helicopter flights at National are not subject to hourly quotas as are commercial airliners.

Residents near the airport, long concerned about the increasing noise of the low-flying machines, expressed new concerns about safety after a helicopter on a photo mission crashed into the Washington Channel on Aug. 21, killing three of the four persons aboard. It fell into the channel just about 100 yards from a string of houseboats and other craft.

Despite those issues, the helicopter business is booming. "The big-dollar executives whose time is valuable enough can justify jumping from rooftop to rooftop," said Jan Allsman, a supervisor in the National Airport control tower, which assigns one controller during the busy hours just to direct helicopters.

"It adds to the complexity of the {air traffic} situation," Allsman said. "But that's why we're here. It's not a problem, it just keeps things interesting."

More than half of the helicopters that used National or its airspace last month were military aircraft serving the Pentagon, Bolling and Andrews Air Force bases, Fort Belvoir and the White House. That represented a 25 percent increase over the year before.

Department of Defense spokesmen would not comment on why the numbers are increasing.

Helicopters make up a small share of local civilian air traffic. On an average weekday, about 20 take off or land at National, or about 2 percent of the roughly 950 aircraft departing or arriving there. At Dulles and Baltimore-Washington international airports, the number of helicopters is so small that it is not recorded separately from other aircraft.

At National, however, helicopter traffic is lifting off. Last month, 827 civilian helicop-ters landed or took off at National, a 27 percent increase over the number in July last year. Another 939 nonmilitary helicopters flew through National's neighborhood, up 12 percent from last year.

By comparison, the airlines flew 16,532 commercial jets in and out of National last month. Private jets and other types of general aviation aircraft accounted for 6,671 landings and takeoffs there.

The whir of helicopters has provoked praise as well as complaints. Accident victims have received increasingly sophisticated and swift medical treatment thanks to hospital choppers.

Most of the traffic growth in recent years comes from corporate executives and emergency rescue agencies, according to the Mid-Atlantic Helicopter Association, local chopper operators and pilots.

Helicopters today serve as a business tool for many executives trying to travel efficiently up and down the heavily congested Northeast corridor between Washington and Boston.

"It's much quicker to fly my helicopter to Wall Street," said Philip Hixon, a partner of Snyder-Hixon Associates, a Bethesda publishing firm with offices in New York City. Since 1979, Hixon has used a chopper to avoid airline delays at National and LaGuardia airports and the traffic jams between LaGuardia and downtown Manhattan.

Because helicopters don't use runways, they can generally take off from National with little wait. At the other end, they can land on Manhattan at a downtown heliport.

Hixon said his trip from National to the door of his New York office takes about two hours, a longer flight time than by airplane but with fewer unpredictable delays. At the end of the day, Hixon walks two blocks from his office to the nearest heliport and takes off.

"You just get in, start up and fly home," Hixon said. "You're out of everybody's way, and it's a beautiful flight."

One measure of the helicopter's value to big business is Manhattan's five public heliports. Additionally, LaGuardia has five helipads compared with National's one.

Many local companies, including The Washington Post Co. in downtown Washington and Mobil Corp. in Fairfax County have helipads on their office rooftops. But because the District has no heliport, most others use National.

Helicopter traffic around Dulles and BWI is expected to grow along with the business communities in those areas, airport officials said. Some commercial real estate developers are considering including helicopter service in the inducements used to attract corporate tenants to large complexes, said R.J. Turner, a vice president of Barrueta & Associates, a Washington real estate brokerage.

Emergency rescue teams and hospitals are the other major source of increasing helicopter traffic, said Jack Thompson, president of the Helicopter Association International.

"Currently, the largest growth in our business is in the emergency medical service industry in general," said John Neilson, director of operations for Omniflight Airways Inc., which maintains and operates 17 helicopters at Martin State Airport near Baltimore. Nine of Omniflight's choppers are devoted to hospital use, he said.

The Washington Hospital Center's Medstar helicopter has seen a 15 percent increase in use over the last year, said Bill McKenna, president of U.S. Jet Aviation, based at National, which maintains and operates that chopper and eight other emergency medical helicopters on the East Coast.

National Airport controllers say the growth of helicopter traffic has not affected air safety because of the way aircraft are monitored and separated from one another.

Throughout the area, helicopters are restricted to different altitudes from other aircraft. Generally, helicopters fly at least 500 feet or more lower than airplanes and are directed by controllers to maintain a horizontal distance of at least 1 1/2 miles from other choppers. Over the Washington Channel, for example, helicopters must fly at an altitude of 200 feet or below.

Helicopters also are generally restricted to defined routes, or pathways in the sky, which follow ground features such as the Beltway, the Potomac and Anacostia rivers and the channel. With permission from the tower, choppers may leave those routes to fly over other areas as they please, without any predetermined flight plan.

But if a whim takes a pilot over the District, the helicopter -- and other aircraft -- must avoid the airspace over the Mall, from the Capitol to the Lincoln Memorial, including the Kennedy Center and the White House.

There have been two helicopter accidents in the District in the past five years, including the one in the channel, according to Federal Aviation Administration records. In the same period, there have been four helicopter accidents in Maryland and 12 in Virginia.

"I feel much safer" in a helicopter than in an airplane, Hixon said. "And they're fun to fly."